Orbital Separation of Charge Order and Superconductivity in La$_{2-x}$Sr$_{x}$CuO$_4$

I. Biało; O. Gerguri; L. Martinelli; J. Küspert; J. Choi; M. Garcia-Fernandez; S. Agrestini; K. J. Zhou; E. Weschke; T. Kurosawa; N. Momono; M. Oda; C. Lin; Q. Wang; J. Chang

arXiv · 2601.01643

Orbital Separation of Charge Order and Superconductivity in La$_{2-x}$Sr$_{x}$CuO$_4$

I. Biało·O. Gerguri·L. Martinelli·J. Küspert·J. Choi·M. Garcia-Fernandez·S. Agrestini·K. J. Zhou·E. Weschke·T. Kurosawa·N. Momono·M. Oda·C. Lin·Q. Wang·J. Chang

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Abstract

We report a combined x-ray absorption (XAS) and oxygen $K$-edge resonant inelastic x-ray scattering (RIXS) study of charge order in underdoped La$_{2-x}$Sr$_x$CuO$_4$ ($x=0.125$) under uniaxial $c$-axis pressure. We find that compressive $c$-axis strain modifies the charge order only within the superconducting state, with a striking polarization dependence: suppression in the $d_{x^2-y^2}$ channel and enhancement in the $d_{z^2}$ channel. X-ray absorption spectra reveal concomitant strain-induced modifications of the oxygen pre-edge and upper Hubbard band, consistent with increased $d_{z^2}$ orbital admixture. Our results suggest that $c$-axis pressure drives an orbital separation between superconductivity, rooted in $d_{x^2-y^2}$ states, and charge order, which gradually shifts to the $d_{z^2}$ channel. This orbital separation reveals a way for superconductivity and charge order to coexist in the cuprates with minimal competition. Furthermore, it suggests that the multi-order phase diagram of La$_{2-x}$Sr$_{x}$CuO$_4$ cannot be realistically described within single band models usually used to describe cuprate physics.

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I. Biało, O. Gerguri, L. Martinelli, J. Küspert, J. Choi, M. Garcia-Fernandez, S. Agrestini, K. J. Zhou, E. Weschke, T. Kurosawa, N. Momono, M. Oda, C. Lin, Q. Wang, J. Chang. 2026-01-04. Orbital Separation of Charge Order and Superconductivity in La$_{2-x}$Sr$_{x}$CuO$_4$. https://arxiv.org/abs/2601.01643

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